Asphalt is a dark brown to black viscous hydrocarbon present in most crude petroleum and in some natural deposits. It is soluble in petroleum products and is generally a byproduct of the petroleum distillation process. Asphalt is often confused with tar, which is produced by coal distillation. Tar is also resistant to petroleum productions.
Generally, asphalt is a waste product from the refinery processing of crude oil and is often called the “bottom of the barrel.” Its boiling point is typically about 350° C. but can be as high as 440° C. Due to its hydrophobic and good adhesive characteristics it is widely used as a binder or cement for stone and rock aggregate in paving and road repair. The term “asphalt cement” (AC) refers to asphalt that has been prepared for use in hot mix asphalt (HMA) and for other paving applications. Asphalt's main components generally comprise: asphaltenes, which are large discrete solid inclusions highly viscous resins which are semi-solid or solid at room temperatures or fluidized when heated, they also become brittle when cold; and oils which are colorless, soluble in most solvents and allow the asphalt to flow.
Approximately 80% of the asphalt consumed in the U.S. is used in road paving. Asphalt road surfaces are widely recycled in the U.S. Approximately 80% of the asphalt from road surfaces that is removed each year is reused as part of the new road, road bed or embankment.
Potholes tend to form in cold weather after a period of snow and ice followed by a thaw. Public crews often have to work in adverse weather, dangerous traffic conditions and need to work on several potholes that appear almost overnight, after a thaw.
Asphalt emulsions that are used in road construction become unstable when ambient temperatures fall below 10° C. As a result, road construction and asphalt manufacturing typically comes to a halt when ambient temperatures are expected to remain at or below 10° C.
In the early 1980s, a new technology to repair potholes was introduced. The process was known as spray injection patching. The process was introduced as a way to perform pothole repairs on roadway surfaces without the need of multiple pieces of expensive equipment, without requiring multiple employees standing on the highway, exposed to traffic and bad weather to repair potholes and the like. When this process was initially introduced, standard asphalt emulsion materials were used. However, there were operational complexities immediately recognized. Thorough cleaning of the emulsion circuit was required on a daily basis, otherwise the equipment could not be used the following day. It was also discovered that the asphalt emulsion characteristics vary by manufacturer, and as a result, the ability to maintain consistent spray patterns and achieve reliability of the equipment presented many challenges.
Asphalt emulsions used in the construction industry have various formulations that are tailored to the various applications, e.g. roofing, flooring, waterproofing, etc. The formulations have different types and amounts of bitumen grades, additives, emulsifiers, etc. depending on the application. Such variations change the physical properties of the emulsion which in turn can change the methods and equipment for handling the material.
As a result of these circumstances and the other known issues of emulsion materials, i.e. the temperature and water issues that are known to the asphalt industry, the injection spray repair process must overcome significant obstacles. Furthermore, such repair systems presently in use are typically performed only when ambient temperature is above 10° C. in order to assure ease of application and to obtain reliable repairs. Such limitations greatly hamper repair and limits the amount of time one is able to work in repairing potholes. It is therefore the goal of the present invention to overcome these obstacles and to provide a composition which may be safely and reliably used at temperatures well below 50° F. and more specifically within a range of −17° F. to 45° F. which occurs, in North America, for example, between October and April, when potholes and the like are known to occur and to require filling and/or repair.